RELATED STORY:EUCOM nominee: More help needed from partner nations in Afghanistan

WASHINGTON — The nominee to head U.S. and NATO forces in Afghanistan wants tens of thousands more national security forces to fight insurgents but does not know if additional U.S. troops will be needed to help in coming years.

“More than 21,000 additional U.S. personnel will be deployed by October this year,” Army Lt. Gen. Stanley McChrystal told members of the Senate Armed Services Committee on Tuesday. “You might ask if that is enough, and I don’t know. It may be some time before I do.”

McChrystal, currently director of the Joint Staff and the former head of Joint Special Operations Command, was tapped to take over the top post in Afghanistan after Gen. David McKiernan was forced out last month.

Lawmakers on the committee said they expect he’ll earn approval in the next few days, but peppered him with questions at his confirmation hearing on how he’ll reverse recent gains by insurgents in southern Afghanistan and on when U.S. forces will be able to leave the country.

McChrystal offered few specifics, praising McKiernan for progress over the last year but still calling the region a haven for violent extremists, drug lords and corrupt government officials. He said he expects attacks on coalition forces to increase as they push into southern insurgent strongholds, and called the next two years a critical time for long-term progress.

He supported increasing the target number of Afghan security forces from 160,000 personnel to well over 200,000, saying the size and population of the country demand more police and national soldiers.

“Although we expect stiff violence ahead, we will not measure success by the number of insurgents killed,” he said. “Rather, we’ll look at the number of Afghans we’ve been able to shield from violence.”

At the hearing, McChrystal also deflected allegations of abuse by special forces troops under his command in Iraq, saying he made sure all interrogation practices were legal, and he reiterated his support for changes already made by the White House.

And he apologized again for his role following the death of Cpl. Pat Tillman, the former NFL star killed in a friendly-fire incident in 2004.

McChrystal was the highest-ranking officer chastised by the Defense Department Inspector General in the investigation into Tillman’s death. The IG report called McChrystal “accountable for the inaccurate and misleading assertions” in the documentation for Tillman’s Silver Star. On Tuesday, McChrystal acknowledged mistakes in editing the Silver Star documentation, but said he had no intention of covering up the fratricide.

The hearing also included Air Force Lt. Gen Douglas Fraser, nominated to take over as commander of the U.S. Southern Command, and Adm. James Stavridis, nominated to head U.S. European Command. Lawmakers stated they expect all three to be easily confirmed.

Stavridis, who would also assume the role of NATO’s Supreme Allied Commander in Europe, said his top priority will be working more closely with partner nations in supplying troops and resources for Afghanistan fight.